MySQL更新时Error Code:1093和Error Code:1175的解决办法

Error Code: 1093. You can't specify target table 'ws_product' for update in FROM clause

这个是我们在使用update或者delete语句时，在where条件里面加入的子查询导致的。例如如下的update语句：

update table set type = 'static' where id in (
select id from ws_product where first_name ='superman'
);

修改上述语句为下面这样，该问题可以解决：

update ws_product set type = 'static' where id in (
select id form (
 select id from ws_product where first_name ='superman'
) xx
);

注意，这样一定要给最里面的子查询定义一个别名，不然会报另外一个错误：

Error Code: 1248. Every derived table must have its own alias

Error Code: 1175. You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column To disable safe mode, toggle the option in Preferences -> SQL Queries and reconnect.

解决办法是在当前session下执行如下的语句

SET SQL_SAFE_UPDATES = 0;

然后再执行Update语句